Relook 400s power supply


Hi all,

I'm trying to fix the power supply on my 400s. It is a DG-50 REV A 2005-11-17.

Can anyone tell me the value of R28(?) and the voltage of zener ZD3?

IMG_20180830_155159 by macplaxton, on Flickr

Also, after removing ZD4 from the board to read the numbers, I noticed it was installed in reverse to the printing on the board. :confused: Anyway, I've check the capacitors and C71 and C23 were bad and I've replaced a few others as a precaution as I had spares.

IMG_20180814_145417_1CS by macplaxton, on Flickr

Relook 400s power to VFD filaments by macplaxton, on Flickr

It seems that pins 1 and 2 of the 15-way connector and +FL and -FL for the vacuum fluorescent display filaments.

Thank you.